Previewing answer-choice options before finishing reading the text is a widely employed test-taking behavior. In the present study we examined whether previewing is related to item response accuracy and response time, using data from Chinese learners of varying English proficiency levels and English native speakers. We examined eye movement patterns of participants who completed online multiple-choice sentence completion tasks, and how previewing was related to reading performance and whether the relation varied as a function of English proficiency level. The results showed that, relative to no previewing, previewing was associated with a significantly lower probability of answering an item correctly but not with significantly longer response time. Importantly, these relations varied across English proficiency levels such that participants with higher proficiency performed better without previewing, but there was no difference for lower-intermediate learners of English. These findings suggest that previewing does not facilitate performance on a sentence comprehension task, but instead interferes with the comprehension process, particularly for individuals with relatively high language proficiency.